The present invention relates generally to adapters for use with packaged devices or other adapter apparatus (e.g., micro lead frame (MLF) devices, chip scale packages (CSP), ball grid array (BGA) packages, land grid array (LGA) or other surface mount devices, male pin adapters, female socket adapter apparatus, etc.).
Certain types of integrated circuit packages are becoming increasingly popular due to their occupancy area efficiency. In other words, they occupy less area on a target board on which they are mounted while providing a high density of contact terminals. For example, one such high density package type is a MLF device.
Generally, such packages contain an integrated circuit having its die bond pads electrically connected to respective conductive surface mount pads that are distributed in a particular configuration on the bottom surface of the package. A target printed circuit board typically has formed on its surface a corresponding configuration of conductive pads which align with the configuration of surface mount pads of the package for electrically mounting the package on the target board. The target board typically includes other conductive traces and elements which lead from the conductive pads used for mounting the package to other circuitry on the target board for connecting various components mounted thereon.
A MLF package is a type of chip scale package (CSP). The die area is a minimum of 80% of the total package area (i.e., the area of the substrate the die is encapsulated in). Further, generally, an MLF package has physical characteristics similar to LGAs, quad flat packages (QFPs), and leadless chip carrier (LCC) type integrated circuit (IC) packages. The MLF package is a leadless design. The interface to the target board is a set of solder pads (e.g., 8-104 pads) on a bottom surface of the package similar to a LGA package. The pads are typically arranged on the perimeter of the package similar to a QFP or LCC type package. MLF packages are generally square or rectangular shaped and have pads along two or four sides of the package on the bottom surface. The pitch between the pads is typically 0.5 mm or less.
Typically, to mount such a package (e.g., MLF package) to a target board, the package is positioned with the configuration of surface mount pads corresponding to the conductive pads on the target board. One or more solder techniques are used (e.g., placement of solder and subsequent heat treatment) to fuse the surface mount pads to the conductive pads of the target board.
Such area efficient packaging (e.g., MLF packages) provide a high density of terminals at a very low cost. Also, this packaging provides for limited lead lengths. Limited lead lengths may reduce the risk of damage to such leads of the package, may provide for higher speed product, etc.
Generally, circuit boards, and/or components mounted thereon, are tested by designers as the circuit boards are being developed. For example, for a designer to test a circuit board and/or a package mounted thereon, the designer must first electrically connect the package to the target circuit board. As described above, this generally includes mounting the package on the target board using a soldering technique to fuse the surface mount pads to the conductive pads of the target board. Therefore, the package may be prevented from being used again.
It is desirable for various reasons to use package adapters for mounting the packages and reuse such packages after testing. For example, such packages may be relatively expensive. Further, for example, once attached, the leads of the package and/or the connection between the surface mount pads of the package and the conductive pads of the target board are not accessible for testing. In addition, it is often difficult to rework the circuit board with packages soldered thereon.
Various adapters which are used for electrically connecting a package to a target printed circuit board are known. For example, U.S. Pat. No. 6,007,348 to Murphy, issued 28 Dec. 1999, entitled “Solder Sphere Terminal,” and U.S. Pat. No. 6,325,280 to Murphy, issued 4 Dec. 2001, entitled “Solder Sphere Terminal,” describe several adapter apparatus for use in mounting ball grid array packages. For example, as described therein, various intercoupling components are provided. In one of such components, an insulative support member includes a plurality of terminal elements positioned within holes extending through the insulative support member. The terminal elements are sized to be press-fit within the holes of the insulative support member.
To gain access to the signals on a target board through an ICs land pattern (e.g., configuration of surface mount pads), it is generally necessary to attach an adapter to the IC's land pattern. Ideally, the adapter is employed such that each signal is brought out individually to a probe point or some other interface which can be connected to with test clips, cables, connectors, etc. Connecting individual wires to an ICs solder pads (e.g., pads of a MLF device) is impossible in most cases due to density concerns and would be extremely time consuming work by a technician (e.g., such work would need to be done with specialized equipment under a microscope). Further, due the density of the pads and the size of the package (e.g., MLF packages or other chip scale packages), various available adapters (e.g., ball grid array type adapters or those similar thereto) are inadequate to achieve access to the signals.